package a10_动态规划;

/**
 * <p>
 * a48_不同的子序列复习3
 * </p>
 *
 * @author flyduck
 * @since 2025/5/15
 */
public class a48_不同的子序列复习3 {
    public int numDistinct(String s, String t) {
        char[] chars1 = s.toCharArray();
        char[] chars2 = t.toCharArray();

        int[][] dp = new int[chars1.length+1][chars2.length+1];

        for (int i = 0; i < chars1.length; i++) {
            dp[i][0] = 1;
        }

        for (int j = 0; j < chars2.length; j++) {
            dp[0][j] = 0;
        }

        dp[0][0] = 1;
        for (int i = 1; i <= chars1.length; i++) {
            for (int j = 1; j <= chars2.length; j++) {
                if(chars1[i-1] == chars2[j-1]){
                    dp[i][j] = dp[i-1][j] + dp[i-1][j-1];
                }else {
                    dp[i][j] = dp[i-1][j];
                }
            }
        }
        return dp[chars1.length][chars2.length];
    }
}
